Why does my TX EQ need to be different for SSB vs FM?

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I've noticed that on my 6700 the TX EQ needs to be adjusted totally different when using SSB vs FM.  This is a PITA when toggling between the two.  I often forget to select a different profile for FM and am told it sounds very high pitched / squawky.  I get great audio reports while using my other rigs regardless of whether I'm on SSB or FM and I do not have to have separate EQ settings for them.

What gives?   Have any of you noticed you need a different EQ for SSB, FM or maybe even AM?   Am I doing something wrong?  I'm using a Heil PR-40 into the BAL plug in the back of the 6700 and the Down East 2N75 LDPA.
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Norm - W7CK

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Posted 3 years ago

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Peter K1PGV, Elmer

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Could this be due to the bandwidth of your transmits signal? How wide are you setting your transmit band pass on SSB?

Peter
K1PGV
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Ken - NM9P, Elmer

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It has to do with the nature of the modulation and the techniques used to maximize intelligibility. On SSB you use higher articulation and compression to increase talk power. This is not necessary on FM, only pure audio with a smoother pattern.

If I forget and leave my processor turned on in FM mode on my other rigs it sounds terrible. Same with the flex. But it is easy to save a profile for FM, just as I do for DX vs. Rag Chewing.
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Norm - W7CK

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This could be the problem.  I'm not currently at home, so I'm unable to check the TX Low and High cut for FM.  I know for SSB I have Low=100 & High=2900.

What should the Low and High cuts be for FM?   How about AM?
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Ken - NM9P, Elmer

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I don't know about "should," but FM commonly has a low frequency cut-off of about 300 Hz so that the voice doesn't conflict with CTCSS tones. I don't have a good recommendation on high end. I would need to look it up for a refresher. But I keep it under 2900 myself., with no compressor, or no more than NOR.
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Ken - NM9P, Elmer

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UPDATE:  I happened by this thread while searching another topic.  For those who haven't noticed, beginning with V.1.6 (I think) Mic Profiles are linked to mode.  So once you have a Mic Profile saved for AM, FM, SSB, FDV, D-Star, RTTY, DIGI, etc, the mode persistence remembers which Mic Profile you last used for that mode.  So now you can save different profiles for each mode and the rig will remember it.

One caveat:  If you have multiple profiles for SSB, for example, (Rag-Chew, DX, Contest, ESSB, Weak-signal) and shift between them depending upon band or conditions, it will remember the last one you used from lat list.  So you will still often need to select your Mic Profile as needed if it differs from your last activity.  But if you only have one profile for FM, then it will use that profile every time you go to FM mode.

Nice!